Why we use graphs and tables
Data is information, like numbers and facts, collected to answer questions. Social studies uses data to learn about populations, weather, money, elections and more.
Graphs and tables organize data so we can understand it quickly, compare things and spot patterns.
Tables
A table organizes information in rows (across) and columns (down).
Population of Canada’s three largest cities (approximate, 2021 census)
| City | Population |
|---|---|
| Toronto | 2.8 million |
| Montréal | 1.8 million |
| Calgary | 1.3 million |
How to read a table
- Read the title.
- Read the column headings.
- Find the row you need and read across.
Bar graphs
A bar graph uses bars to compare amounts. Longer or taller bars mean bigger amounts.
Favourite season in our class
| Season | Votes |
|---|---|
| Summer | ████████ 8 |
| Winter | █████ 5 |
| Fall | ████ 4 |
| Spring | ███ 3 |
Summer is the most popular; spring is the least.
Parts of a bar graph
- Title: what the graph is about
- Axis labels: each axis is a line along the side or bottom; the labels tell what is being measured
- Scale: the numbers along an axis, which count by equal steps (1, 2, 5, 10…)
- Bars: show the data
Line graphs
A line graph shows how something changes over time. Points are connected with a line.
Average monthly temperature in Winnipeg (°C, approximate)
| Month | Jan | Mar | May | Jul | Sep | Nov |
|---|---|---|---|---|---|---|
| Temperature | −16 | −6 | 12 | 20 | 12 | −6 |
If you plotted these, the line would rise from winter to summer, then fall again. Line graphs are great for showing trends, like population growth or temperature.
Pictographs
A pictograph uses pictures or symbols. A key tells what each symbol means.
Books read by each group (📕 = 2 books)
| Group | Books |
|---|---|
| Red | 📕📕📕📕 (8) |
| Blue | 📕📕📕 (6) |
| Green | 📕📕📕📕📕 (10) |
Watch out: if one symbol = 2, then half a symbol = 1.
Pie charts
A pie chart (circle graph) shows parts of a whole. Each slice is a fraction or percentage of the total. All slices add up to 100%.
How Sam spends a $20 allowance
| Category | Amount | Share |
|---|---|---|
| Saving | $10 | half (50%) |
| Spending | $6 | 30% |
| Sharing | $4 | 20% |
The saving slice would take up half the circle.
Which graph should I use?
| Want to show… | Use a… |
|---|---|
| exact numbers to look up | table |
| comparisons between groups | bar graph |
| change over time | line graph |
| a fun, simple comparison | pictograph |
| parts of a whole | pie chart |
Reading graphs carefully
Ask:
- What is the title?
- What do the labels and scale show?
- What is the biggest and smallest?
- Is there a pattern or trend?
- What conclusion can I make?
Be careful: a graph’s scale can make differences look bigger or smaller than they are. Always check where the numbers start.
Try it yourself
- Survey your class about favourite pets. Make a table and a bar graph.
- Track the temperature outside each day for a week and make a line graph.
- Make a pictograph of how you get to school, with a key.
- Draw a pie chart showing how you spend a typical day: sleep, school, play, meals.
Quick recap
- Data is information collected to answer questions.
- Tables organize data in rows and columns.
- Bar graphs compare amounts; line graphs show change over time.
- Pictographs use symbols with a key; pie charts show parts of a whole.
- Always read the title, labels and scale.